System and method for non-contact metrology of surfaces

摘要

A non-contact metrology system utilizes a display that can be programmed with a plurality of targets. The display targets shine on a specular surface and the reflected targets are detected by an imaging device. Based on the display pattern and the expected location of the reflected pattern, it is possible to characterize the reflective surface. The displayed pattern can be a regular array of targets and the reflected pattern detected by the imaging device is an irregular display of targets whose locations are based on the particular display pattern, the location of the display system and imaging device and the nature of the surface. Deviations of the actual location of targets from the expected location of targets is indicative of unexpected variations in the surface. Alternatively, the display has an irregular pattern of targets such that the reflected signals result in a regularly spaced array detected by the imaging device.

主权项

1. A non-contact metrology system to measure a surface, comprising:
a display positioned proximate a first side of the surface to be measured; a pattern generator configured to generate a pattern for display on the display, the pattern having a plurality of spot targets being arranged in two dimensions with each of the plurality of targets being separated from others of the plurality of targets in a first dimension and each of the plurality of targets being separated from others of the plurality of targets in a second dimension orthogonal to the first dimension; an imaging device positioned to detect at least a portion of the plurality of targets after interaction with the surface and to generate an electronic image thereof; an image analyzer configured to analyze the electronic image to determine if the plurality of targets in the electronic image are in expected locations in each of the two dimensions following interaction with the surface wherein the pattern generator is configured to generate the plurality of targets in an irregularly-spaced display pattern; and wherein the expected locations of the plurality of targets are in a regularly-spaced display pattern based on a location of the display with respect to the surface, a location of the imaging device with respect to the surface, and a shape of the surface.